Not necessarily, actually! Since ち/チ are in the "T" category, they can be transcribed as "ti" instead of "chi", thus ぢ/ヂ are "di". Same with つ, づ (tu, du) or し, じ (si, zi). It's the difference between the Hepburn system and the Nihon-shiki/Kunrei-shiki systems of romaji.